This morning, the signal engineer will submit the draft plan for Newburyport to the Superintendent.



Operationally, I need signals in Bexley more than I do Newburyport, but designing it gave me a better understanding of how to protect

non-powered turnouts and use diodes to partition the logic. The one on this diagram is keeping westbound Block 14's detector and

turnouts from affecting the eastbound signals.

I am cheating a bit, as the 17w stagger block will show double yellow when 16w0 is red, instead of yellow over red. And because block

17 is signaled EB only, 16e shows bottom yellow (call-on) when the double track turnout is normal, regardless of 17's occupancy. Either

could be fixed with another SD-3 driver.

Anyway, it felt good to finish this today, as the LED power supply is still frustrating me.

After I posted, I noticed I'd cut off the SD-3 labels. From the left, they are SD12e, SD17w, SD16w and SD16e.

Also, thanks Pete, Mike and Dave. I'm out where the streetcars don't run again, and it's good to know there's

someone who knows where I went into the woods.

I'm going to try and follow along here for this one. My new 10 x 20 layout plan im looking at signalling options prior to building. I want to make sure i allow for it properly before i put in all the hard work. Do keep posting this information.

Thanks, Adrian. Feel free to ask questions. I'm figuring this out on the fly and anything that isn't clear might not have been thought through. Better to fix it on paper than after it's wired.

Notation (it seems obvious to me, but I devised it):

Block IDs are 2-digit numbers. 09 through 16 figure in the Newburyport plan.

Turnout IDs are block_id T sequence_from_west, so 14T2 (the Hytron spur) is the second turnout in block 14.

Signal IDs are block_id end sequence, so 16e is the home signal at the east end of block 16. 16w0 is the home signal at the west end, and 16w1 is the 'against the current of traffic' fixed red dwarf.

Signal driver IDs add SD to the signal ID, e.g. SD16w0 and SD16e.

Relay IDs add an R to the turnout ID. Only power operated turnouts have relays. Others have a contact on the mechanism to ground appropriate SDs' "Red" inputs.

Detectors ground their output to indicate 'occupied'. Signal drivers operate off grounds at their Red and Yellow inputs. Turnout control is completely independent of the signals.

I'm following prototype practice generally, which is why you'll see electrical block boundaries without signals. It is well known that the B&M didn't do anything like it was made out of money. If a possible signal location wasn't going to earn its keep, the function was implemented on the signal to the rear. This is why there isn't a 14e; 16e does that job. There was little operational reason for EB moves on the WB track at the end of double track, so the dwarf was fixed red. If you needed to pass it, you called the drawbridge operator for permission.

There will be some shortcuts, mostly limitations on displayed aspects and not bothering to display track occupancy on most of the dwarfs. Any current train crew who operate here will have been using NORAC rules for at least 25 years, if not their entire career, so my pre-NORAC RR shouldn't trouble their reflexes. If a retired B&M signal maintainer should comment, I'll be happy to listen; it's all modular so $20 for another SD-3 and a few hours designing the changes and implementing them won't be a big burden. But right now I want to prove feasibility and get the basic system up and running.

I like your solution for block, turnout and detector numbering. I'm from a electrical power systems background and design a lot of control wiring and things. Ive been thinking for a fw weeks of how to label my feeders ect for my layout. I know its overkill but for me identification and trouble shooting problems from a drawing is what i know.

After looking reading the way you had identified the components its got me drawing a schematic rather then a layout plan as i continue to work on my plans so cheers.

Thanks; there will be one change to Newburyport before I start implementing it: I'm being inconsistent about 0-based (signal) and 1-based (turnout) numbering. I haven't decided which to change, but working on the bi-directional double track for Bexley brings it out.

OK, now I'm confused. This is probably a "Normal" condition for me, but let's see if we can "reverse" it. As it were....

What's inconsistent in Newburyport? Your notation scheme seems entirely logical to me, for the most part. I'm not sure about numbering anything with a zero, but I'm apparently missing the Major Issue here.

Pete

in Michigan

James,

Please check your PM box. Thanks.

Pete

in Michigan


edit: correcting "autocorrect."

It's a computer programmer thing - when you're numbering items, is the first one #0 or #1? Most people would say '1', but if you're using the number as an index into an array (a bunch of identical objects stored next to each other in memory), '0' saves a couple of math operations every time you touch an object. That may matter a lot if the objects are heavily used.

In this case, there's no benefit for counting zero-based vs. one-based, and mixing the schemes reduces consistency and clarity. So I'll convert signal numbering to 1-based.

Whatever works. It took me a long time (as in decades) to get my head around the idea that numbers are a concept, not an absolute, so if saving time, calculations and electrons is the result of starting with zero for something physical that any first-grader "knows" is number "One," I'd say go for it!

But that's me....

Pete

in Michigan

During last week's NRHS convention in Rutland, VT I worked on the Bexley signal plan during some idle time:



7T5 and 7T4 are SPDT contacts on the hand-throw mechanisms entering the yard and enginehouse. rDC and yDC are the positive and negative feeds for the bi-color dwarfs I'll use.

This does about 90% of what I want, but I don't have enough contacts on the crossover relay (R6X2) to provide 'call on' (Bottom Yellow) indications on signals 05W, 06W1 and 06W2 at the interlocking's west entrance. I'll sleep on it before embarking on a redraw.

I was feeling happy about progress on dwarf signals ( https://railroad-line.com/node/28096 ) so I went to work on designs that use them:



My staging is open and easy to see, so I'm not bothering with detection. I don't really need departure signals either. The east end signals will only indicate Stop or Approach, but the westbound home signal will change between High and Middle Yellow depending on the crossover position. The west end's signals are covered in the single Newburyport drawing since they don't interact with the east end's.

The mechanism slide switches on 01T2 and 02T2 are using all their contacts for the swing blocks & frogs. Adding a couple of SPDT microswitches to their mechanisms shouldn't take an unreasonable amount of under-layout time, though.

And an oops: :erm: The dwarf at the west end of the East Lead should be 'D3e', not 'D2e'. I've fixed the plan's track schematic and diagram for 01T2 but I really should build some more dwarves instead of fixing the screenshot above.

I finally got the first interlocking working: Robinson Rd., the east entrance to Bexley yard. This was after burning up the two dwarfs one more time (wiring error, should have documented the actual interlocking board better):



Here's the removable board with the SD-3, relay and DCOD detector, as installed. Next I'll start on Newburyport, but I can't finish it till Oregon Rail Supply fixes an out-of-stock condition at Walthers.

Back to work on the signals: East Bexley interlocking has proven helpful at my last two op sessions, so it's not just for show. And

over the past 4 months I've accumulated everything I need to complete the north end of the room:



I've re-drawn Newburyport to show inter-signal cabling. The longer segments can be done with telco 'quad'. The six wires needed from

Newburyport West across the Merrimack River to Draw will be recycled ethernet cable. The lines from block detectors D14, D16 & D17 come

from the Draw panel because the Olin's Depot detector assumes common rail and I have to put it on the feed side of my anachronistic block toggles.

While I'm building the signals and working out how to make them removable using DIP in-line sockets, I'll add the wire colors to be used

for each circuit to the drawing. And fix the 'connection' dots so they show on screen captures and printouts.

I'd been wanting to get back to work on my signals, and Sunday's op session emphasized the benefits I'm hoping for. So I spent the last

couple of days implementing the Newburyport diagram above. It's not finished, but one bit of engineering has been demonstrated and I've

figured out how to address long-haul wiring.

I'd always considered it important that signals react to the position of turnouts. So back when I was building my hand-throw turnouts in

Newburyport, I used DPDT slide switches. One xfer contact for the frog, the other for signals.



Today's wiring got me Stop (three red) at Robinson Rd. when this turnout is reversed, and Caution (high yellow) when a turnout in the

next block is reversed. The center pole is DC ground, the 'closed when reversed' goes to Block 15 Occupied (see below).

If I was doing this 20 years ago, I could have scrounged any quantity of telco 25-pair cable from office renovations. With some 50-foot

scraps, I'd have used different wire colors for every circuit. But what I had today was telco 'quad'.



Now I'm enlightened about how prototype signaling worked. The same positions on the crossarms would often carry different circuits

in advance of a signal vs. in the rear. I'm doing the same with quad under the layout: To the left, Green is Block 15 Occupied, to the

right Green is Block 14 Occupied. Yellow carries Block 17 Occupied through.

I'm noting all this on my printed drawings, to be copied onto the machine-readable files Real Soon Now.